1. Field of the Invention
The invention relates to an integrated structure of passive elements, and particularly to an integrated structure of passive elements in an LLC resonance converter realized by flexible circuit boards.
2. Description of the Related Art
In recent years, the trend for developing “light, thin and small” consumer electronic products has compelled the development of power electronic converters with higher and higher power density. In order to achieve a high power density, the key is how to reduce the volume size of passive elements, because the passive elements account for most of total volume in a power electronic converter. Working at a high frequency is an important direction in reducing the volume of the passive elements.
Another direction is the integration of passive elements. ZL 02801543.6, corresponding to PCT international publication no. WO 02/093593 and U.S. Pat. No. 6,528,859, proposed a short-form inductor-capacitor power processor wound by a metal foil, which realized the integration of inductors and capacitors.
However, power electronic converters, especially the power electronic converters used in consumer electronic products, due to safety considerations, are usually required to adopt transformer isolation. Therefore, if the integration of transformers, inductors and capacitors can be achieved, it will provide an integration of passive elements of a wider range and will be of greater significance.